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Although melanoma is amenable to early detection, there has been no decline in the mortality rate of this disease and the prognosis of patients with high-risk primary melanoma or with macroscopic nodal involvement remains poor. The best option for patients with higher-risk melanoma is to receive effective adjuvant therapy in order to reduce their chances of recurrence. Multiple systemic therapeutic agents have been tested as adjuvant therapy for melanoma with durable benefits seen only with interferon- to date. More recently ipilimumab at the high dose of 10 mg/kg has shown a significant improvement in terms of Relapse free survival and Overall survival for stage III melanoma patients but at a significant cost in terms of immune-related toxicities. More recently, novel treatment options have emerged. The results from the latest trials with immunotherapy (PD-1 inhibitors) and molecular targeted therapy (BRAF inhibitor + MEK inhibitor) have revolutionized the management of adjuvant treatment for melanoma. As the results from these trials will mature in the next years, a change in the landscape of adjuvant treatment for melanoma is expected, resulting in new challenges in treatment decisions such as optimizing patients’ selection through predictive and prognostic biomarkers, and management of treatment related adverse events, in particular immune related toxicities.

Background: Autoimmune hypophysitis is a frequent immune-related adverse event (irAE) in cancer patients treated with immunecheckpoint inhibitors. Studies seeking anti-pituitary (APA) and anti-hypothalamus (AHA) antibodies in patients treated with anti-PD-1 and anti-PD-L1 are scarce. The aim of this study is to search for APA and AHA and related pituitary dysfunction in patients treated with these agents. Methods:Cross-sectional and preliminary longitudinal studies were conducted at the Medical Oncology Unit and Endocrinology and Metabolic Diseases Unit of the University of Campania “Luigi Vanvitelli”. Fifty-four cancer patients on treatments with anti-PD-1 or anti-PD-L1 (Group 1) and 50 healthy controls were enrolled for a cross-sectional study, 13 cancer patients (Group 2) were enrolled for our preliminary longitudinal study. APA/AHA titers and changes in biochemical and hormonal profile were evaluated in Group 1, in Group 2, they were evaluated before and after nine weeks from the start of immunotherapy. Results: Patients of Group 1 showed a higher prevalence of APA and AHA than controls: 21 of them had APA, 16 had AHA, and 11 had both autoantibodies. In total, 7 of 13 patients in Group 2 became APA-positive and 3 became AHA-positive after nine weeks of immunotherapy, showing an increase in prolactin and a decrease in ACTH and IGF-1 levels compared with basal values. Conclusions:Anti-pituitary and anti-hypothalamus antibodies seem to play a pivotal role in hypothalamic–pituitary autoimmunity and secondary endocrine-related alterations evoked by anti-PD-1 and PD-L1 antibodies.

Melanoma is a form of skin cancer that is frequently diagnosed at early stages. In most cases, surgical resection is curative. In case of thicker melanomas (> pT1b) without clinical or instrumental evidence of metastasis, a sentinel lymph node biopsy is recommended for staging purposes. If the lymph nodes are the only site of disease (macroscopic or microscopic> 1mm), configuring stage III, the international guidelines recommend the use of adjuvant therapy with checkpoint inhibitors (nivolumab or pembrolizumab) or targeted therapies (dabrafenib plus trametinib). These drugs have shown a significant increase in recurrence-free survival, although some doubts and open questions remain. Specifically, none of the available treatments has shown a clear benefit in the overall survival rates, the advantages they give in stage IIIA are not well known, and finally there are still no prospective clinical studies identifying the best approach to continue the therapeutic process in case of relapse. Furthermore, there are new opportunities opening up with the upcoming results of the neoadjuvant trials that could revolutionize the treatment of clinically evident stage III melanoma.

Tumor heterogeneity represents a possible cause of error in detecting predictive genetic alterations on tumor tissue and can be overcome by testing alterations in circulating tumor DNA (ctDNA) using liquid biopsy. We assessed 72 consecutive patients with a diagnosis of metastatic colorectal cancer (mCRC) using Idylla&trade, Biocartis, a fully automated platform that evaluates the most frequent mutations of KRAS, NRAS and BRAF genes. We correlated the results of liquid biopsy and standard tissue-based next generation sequencing (NGS) analyses to patient clinical features. The overall agreement was 81.94%. Concordance was 85.71% and 96.15% in treatment-na&iuml, ve patients and in the patient subgroup with liver metastases, respectively. In liver metastases positive, treatment-na&iuml, ve patients, sensitivity, specificity and positive predictive value (PPV) were 92.31%, 100% and 100%, respectively. Circulating mutational fraction (CMF) was significantly higher in patients with liver metastases and high carcinoembryonic antigen (CEA) levels. In a subgroup of patients pre-treated with anti-Epidermal Growth Factor Receptor (EGFR) agents, emerging KRAS mutations were evidenced in 33% of cases. Testing RAS/BRAF mutations on plasma using the Idylla&trade, Biocartis platform is feasible and reliable in mCRC patients in clinical practice.

BRAF-V600 mutations occur in approximately 50% of patients with metastatic melanoma. Immune-checkpoint inhibitors and targeted therapies are both active as first-line treatments in these patients regardless of their mechanisms of action and toxicities. However, an upfront therapeutic strategy is still controversial. In fact, waiting for results of ongoing clinical trials and for new biomarkers, clinicians should base their decision on the clinical characteristics of the patient and on the biological aspects of the tumor. This review provides an overview on BRAF-V600 mutations in melanoma and will discuss their prognostic and clinical significance. Moreover, it will suggest a therapeutic algorithm that can drive therapeutic choice in a first-line setting for BRAF-V600 mutant melanoma patients.

Background Targeting the epidermal growth factor receptor (EGFR) either alone or in combination with chemotherapy is an effective treatment for patients with RAS wild-type metastatic colorectal cancer (mCRC). However, only a small percentage of mCRC patients receive clinical benefits from anti-EGFR therapies, due to the development of resistance mechanisms. In this regard, HER2 has emerged as an actionable target in the treatment of mCRC patients with resistance to anti-EGFR therapy. Methods We have used SW48 and LIM1215 human colon cancer cell lines, quadruple wild-type for KRAS, NRAS, BRAF and PI3KCA genes, and their HER2–amplified (LIM1215-HER2 and SW48-HER2) derived cells to perform in vitro and in vivo studies in order to identify novel therapeutic strategies in HER2 gene amplified human colorectal cancer. Results LIM1215-HER2 and SW48-HER2 cells showed over-expression and activation of the HER family receptors and concomitant intracellular downstream signaling including the pro-survival PI3KCA/AKT and the mitogenic RAS/RAF/MEK/MAPK pathways. HER2-amplified cells were treated with several agents including anti-EGFR antibodies (cetuximab, SYM004 and MM151); anti-HER2 (trastuzumab, pertuzumab and lapatinib) inhibitors; anti-HER3 (duligotuzumab) inhibitors; and MEK and PI3KCA inhibitors, such as refametinib and pictilisib, as single agents and in combination. Subsequently, different in vivo experiments have been performed. MEK plus PI3KCA inhibitors treatment determined the best antitumor activity. These results were validated in vivo in HER2-amplified patient derived tumor xenografts from three metastatic colorectal cancer patients. Conclusions These results suggest that combined therapy with MEK and PI3KCA inhibitors could represent a novel and effective treatment option for HER2-amplified colorectal cancer. Electronic supplementary material The online version of this article (10.1186/s13046-019-1230-z) contains supplementary material, which is available to authorized users.

Background Colorectal cancer (CRC) has been shown to acquire RAS and EGFR ectodomain mutations as mechanisms of resistance to epidermal growth factor receptor (EGFR) inhibition (anti-EGFR). After anti-EGFR withdrawal, RAS and EGFR mutant clones lack a growth advantage relative to other clones and decay; however, the kinetics of decay remain unclear. We sought to determine the kinetics of acquired RAS/EGFR mutations after discontinuation of anti-EGFR therapy. Patients and methods We present the post-progression circulating tumor DNA (ctDNA) profiles of 135 patients with RAS/BRAF wild-type metastatic CRC treated with anti-EGFR who acquired RAS and/or EGFR mutations during therapy. Our validation cohort consisted of an external dataset of 73 patients with a ctDNA profile suggestive of prior anti-EGFR exposure and serial sampling. A separate retrospective cohort of 80 patients was used to evaluate overall response rate and progression free survival during re-challenge therapies. Results Our analysis showed that RAS and EGFR relative mutant allele frequency decays exponentially (r2=0.93 for RAS; r2=0.94 for EGFR) with a cumulative half-life of 4.4 months. We validated our findings using an external dataset of 73 patients with a ctDNA profile suggestive of prior anti-EGFR exposure and serial sampling, confirming exponential decay with an estimated half-life of 4.3 months. A separate retrospective cohort of 80 patients showed that patients had a higher overall response rate during re-challenge therapies after increasing time intervals, as predicted by our model. Conclusion These results provide scientific support for anti-EGFR re-challenge and guide the optimal timing of re-challenge initiation.

Colorectal cancer; Epidermal growth factor receptor (EGFR); MAPK pathway Càncer colorectal; Receptor epidèrmic de factor del creixement (EGFR); Via MAPK Cáncer colorrectal; Receptor epidérmico de factor del crecimiento (EGFR); Vía MAPK BACKGROUND: Previous studies showed that the combination of an anti-Epidermal growth factor (EGFR) and a MEK-inhibitor is able to prevent the onset of resistance to anti-EGFR monoclonal antibodies in KRAS-wild type colorectal cancer (CRC), while the same combination reverts anti-EGFR primary resistance in KRAS mutated CRC cell lines. However, rapid onset of resistance is a limit to combination therapies in KRAS mutated CRC. METHODS: We generated four different KRAS mutated CRC cell lines resistant to a combination of cetuximab (an anti-EGFR antibody) and refametinib (a selective MEK-inhibitor) after continuous exposure to increasing concentration of the drugs. We characterized these resistant cell lines by evaluating the expression and activation status of a panel of receptor tyrosine kinases (RTKs) and intracellular transducers by immunoblot and qRT-PCR. Oncomine comprehensive assay and microarray analysis were carried out to investigate new acquired mutations or transcriptomic adaptation, respectively, in the resistant cell lines. Immunofluorescence assay was used to show the localization of RTKs in resistant and parental clones. RESULTS: We found that PI3K-AKT pathway activation acts as an escape mechanism in cell lines with acquired resistance to combined inhibition of EGFR and MEK. AKT pathway activation is coupled to the activation of multiple RTKs such as HER2, HER3 and IGF1R, though its pharmacological inhibition is not sufficient to revert the resistant phenotype. PI3K pathway activation is mediated by autocrine loops and by heterodimerization of multiple receptors. CONCLUSIONS: PI3K activation plays a central role in the acquired resistance to the combination of anti-EGFR and MEK-inhibitor in KRAS mutated colorectal cancer cell lines. PI3K activation is cooperatively achieved through the activation of multiple RTKs such as HER2, HER3 and IGF1R.

Background Molecular mechanisms driving acquired resistance to anti-EGFR therapies in metastatic colorectal cancer (mCRC) are complex but generally involve the activation of the downstream RAS-RAF-MEK-MAPK pathway. Nevertheless, even if inhibition of EGFR and MEK could be a strategy for overcoming anti-EGFR resistance, its use is limited by the development of MEK inhibitor (MEKi) resistance. Methods We have generated in vitro and in vivo different CRC models in order to underline the mechanisms of MEKi resistance. Results The three different in vitro MEKi resistant models, two generated by human CRC cells quadruple wild type for KRAS, NRAS, BRAF, PI3KCA genes (SW48-MR and LIM1215-MR) and one by human CRC cells harboring KRAS mutation (HCT116-MR) showed features related to the gene signature of colorectal cancer CMS4 with up-regulation of immune pathway as confirmed by microarray and western blot analysis. In particular, the MEKi phenotype was associated with the loss of epithelial features and acquisition of mesenchymal markers and morphology. The change in morphology was accompanied by up-regulation of PD-L1 expression and activation of EGFR and its downstream pathway, independently to RAS mutation status. To extend these in vitro findings, we have obtained mouse colon cancer MC38- and CT26-MEKi resistant syngeneic models (MC38-MR and CT26-MR). Combined treatment with MEKi, EGFR inhibitor (EGFRi) and PD-L1 inhibitor (PD-L1i) resulted in a marked inhibition of tumor growth in both models. Conclusions These results suggest a strategy to potentially improve the efficacy of MEK inhibition by co-treatment with EGFR and PD-L1 inhibitors via modulation of host immune responses.

3578 Background: Promising antitumor activity of so called rechallenge treatment with anti-epidermal growth factor receptor (EGFR) drugs in patients with RAS wild type (RAS WT) metastatic colorectal cancer (mCRC) has been recently reported. Beside the absence of resistance mutations at plasma circulating tumor DNA (ctDNA) analysis, no biomarkers of response to anti-EGFR rechallenge strategy have been identified. Methods: We conducted the single arm phase II CAVE mCRC trial to evaluate the combination of cetuximab as rechallenge plus avelumab treatment in 77 RAS WT mCRC patients, with complete (CR) or partial response (PR) to first line chemotherapy plus anti-EGFR drugs, who developed acquired resistance and received a subsequent line of therapy. A post-hoc baseline analysis of circulating tumor DNA (ctDNA) for KRAS, NRAS, BRAF and EGFR-S492R mutations was performed for 67/77 (87%) patients. The correlation of skin toxicity (ST) and other clinical variables with OS, PFS and response rate (RR) was assessed. Results: Cetuximab plus avelumab provided in the intention to treat population (ITT) median overall survival (mOS) of 11.6 months [95% Confidence Interval (CI), 8.4-14.8] and median PFS (mPFS) of 3.6 months (95% CI, 3.2-4.1) with a manageable toxicity profile. Thirty-three (42.9%) patients experienced grade 2-3 ST with mOS of 17.8 months (CI 95% 14.9-20.7), whereas 44 (57.1%) patients with grade 0-1 ST exhibited mOS of 8.2 months (CI 95% 5.6-11), (HR 0.51, CI 95% 0.29-0.89, P = 0.019). mPFS was 4.6 months (CI 95% 3.5-5.8) in patients with grade 2-3 ST, compared to 3.4 months (CI 95% 2.8-4.1) in patients with grade 0-1 ST (HR 0.49, CI 95% 0.3-0.8, P = 0.004). Grade 2-3 ST and baseline RAS/BRAF/EGFR WT ctDNA were the only variables with statistically significant effect on OS both at univariate and multivariate analyses. ST, number of metastatic sites ≤2, surgery of primary tumor and RAS/BRAF/EGFR WT ctDNA were associated with an improvement in PFS only at univariate analysis. In the 33 patients with grade 2-3 ST, 1 (3%) CR, 2 (6.1%) PR and 24 (72.7%) stable disease (SD) were observed, with disease control rate (DCR) of 81.8%. In the 44 patients with grade 0-1 ST 0 CR, 3 (6.8%) PR, 20 (45.5%) SD, with 52.3% DCR were reported. Conclusions: Cetuximab plus avelumab is effective and well tolerated as rechallenge treatment in mCRC. ST is a clinical biomarker for the identification of RAS/BRAF mCRC patients that could benefit from anti-EGFR rechallenge. Clinical trial information: NCT04561336.

3594 Background: Recently, in metastatic colorectal cancer (mCRC), the detection of RAS mutations by circulating tumor (ct) DNA has recently emerged as a valid and non-invasive alternative approach, overall showing a high concordance with the standard tissue genotyping, giving information on response to EGFRi treatment and resistant mechanisms. However, RAS mutations may be missed due to low levels of any ctDNA in the blood (false-negative), and it has been difficult to distinguish this from patients without a RAS mutation in the tumor (true-negative). We propose a methodology that can be applied to multi-gene ctDNA testing panels to accurately distinguish true- and false-negative tests. Methods: 357 subjects with tissue and multi-panel ctDNA testing from MD Anderson (MDACC) were used as a training dataset and 295 subjects from Massachusetts General Hospital (MGH) dataset as the testing dataset. CtDNA panels contained between 65 and 70 genes, allowing evaluation of tumor ctDNA shedding from variant allele fraction (VAF) levels in the plasma from other genes (such as APC and TP53). Based on the relationship between KRAS and the VAFs of other gene, we established a Bayesian model providing a posterior probability of false negative in the ctDNA test, using thresholds of < 5% (low), 5-15% (medium), and > 15% (high). This model was validated on the MGH database. Results: Across both cohorts, 431 patients were ctDNA wild type for KRAS. Of those, 29 had tissue documenting a KRAS mutation for a false negative rate of 8%. The model provides the posterior probability that a KRAS mutation is indeed present in the tissue given the observed values of allele frequencies for other mutated genes in the plasma. In the validation cohort, a predicted low false negative had no false negatives (0/62, 95% CI 0%-5.8%), while a predicted medium false negative rate was associated with 3% false negative (1/32, 95% CI 0%-16%). In contrast, a high predicted false negative rate was associated with 5% false negative (5/100, 95% CI 1.6%-11%). The results demonstrate the ability of our tool to discriminate between subjects with true negative and false negatives, as a higher proportion of false negatives are observed at higher posterior probabilities. Conclusions: In conclusion, our approach provides increased confidence in KRAS ctDNA mutation testing in clinical practice, thereby facilitating the identification patients who will benefit from EGFR inhibition while reducing the risk of false negative tests. Extension of this methodology to NRAS and BRAF is possible, with clinical application enabled by a freely available online tool.

3514 Background: Colorectal cancers (CRC) lacking RAS MTs treated with EGFRi are thought to evolve by a repetitive process of genetic diversification and clonal evolution. Acquired MTs in KRAS, NRAS, BRAF, MAP2K1, and EGFR are known mechanisms of acquired resistance in the EGFRi refractory population. However, the prevalence of MTs in the first line (1L) setting is not well established as most experience with EGFRi has been beyond the 1L setting. Methods: We analyzed paired plasma samples from RAS/BRAF/EGFRWT mCRC patients (pts) enrolled in 3 large randomized phase 3 trials who had been treated with EGFRi and in whom paired baseline (BL) and time of progression (PRO) plasma samples had been collected for sequencing of ctDNA on a platform optimized for very low allele frequencies (Plasma Select-R™ and Resolution Bio™). Prevalence of MTs at BL and PRO from a 1L study (‘203; FOLFOX ± panitumumab) were compared with 2 studies in the third line setting (3L; ‘007; panitumumab + best supportive care [BSC] vs BSC; and 3L; ‘763; panitumumab vs. cetuximab), to assess the frequency of acquired resistance mutations via ctDNA analysis. Results: For pts with available paired plasma samples (n = 112 for ‘203; n = 89 for ‘007; n = 274 for ‘763), acquisition of at least one KRAS, NRAS, BRAF, MAP2K1, or EGFR MT was significantly less common in post-progression samples in the EGFR containing arms of the 1L ‘203 study compared to the 3L ‘763 and ‘007 studies (6.8% vs 50.4% vs 39.6%, respectively; p < 0.001). In the non EGFR containing arms of the ‘203 and ‘007 study, the rate of acquired MTs was 7.5% and 0%, respectively (p = 1). While this difference in the rate of acquired MTs between the EGFR and non EGFR containing arms was statistically significant for the 3L study (p < 0.001) it was not significant for the 1L study. Further, pts on both 3L studies treated with EGFRi who experienced CR, PR or SD acquired more MTs than those who had PD as best response (53.6% vs 33.3%, respectively; p < 0.001). This relationship was not significant in the 1L setting (7.7% vs 0%; p = 1). Subclonal MTs (rMAF < 25%) in KRAS, NRAS, EGFR, BRAF and MAP2K1 were present at BL in 129 pts (27%). Based on the hypothesis that EGFRi is selecting for rare existing mutated cells in the tumor, we would expect expansion of any preexisting subclones in the BL samples. However, in contrast to expectations, these subclones rarely expanded to become clonal at the time of progression (12.4%). Conclusions: In contrast to expectations, acquired KRAS, NRAS, BRAF, EGFR, or MAP2K1 MTs rarely develop after 1L therapy. While selective pressure appears to increase the frequency of acquired MTs in the 3L setting, preexisting subclonal MTs do not appear to be the dominant source of acquired MTs at progression, implying that there may also be a transient mutational process driving resistance rather than expansion of preexisting clones. These findings have significant implications for ongoing and planned EGFRi rechallenge studies.

110 Background: BRAFV600E mutation identifies mCRC patients with poor prognosis with only little benefit from standard therapy. Analysis from TCGA revealed that 89% of BRAFV600E CRC tumors were associated with a high CpG island methylator phenotype (CIMP-H), which may result in epigenetic silencing of tumor suppressor genes, while only 29% of BRAF wild-type tumors are CIMP-H. In this study, we define key pathways regulated by global DNA hypermethylation in the context of BRAFV600E mutation. Methods: We analyzed the TCGA Illumina 450k array methylation datasets and RNA-sequencing datasets for 97 CIMP-H CRC tumors (27 BRAFV600E; 69 BRAF WT) identified by five universal CIMP annotations ( p14, p16, MLH1, MINT1, MINT2, MINT31). We defined differential methylation profile according to BRAF mutation status and calculated Spearman correlation between methylation and gene expression to identify CIMP-H BRAF-associated genes. Next, pathways enriched with CIMP-H BRAFV600E tumors were defined using PANTHER pathway analysis. Additionally, β-catenin IHC were conducted on 145 MD Anderson CRC patient samples and compared by CIMP and BRAF status. Results: BRAF mutation is associated with lower rates of APC mutation as has previously been shown (32%, 82%). We identified 6,097 differentially methylated probes by BRAF mutation status (FDR = 10-4), and as expected, our data suggests a higher methylation profile in BRAFV600E mutated tumors compared to BRAF WT. Intriguingly, CIMP-H BRAF-associated genes showed enrichment in the Wnt-signaling and cadherin signaling pathways ( p< 0.0001 (FDR < 0.0001)). Despite the epigenetic Wnt-signaling, nuclear β-catenin expression (as a measure of Wnt activity) in CIMP-H and BRAF tumors remains lower than for non-CIMP, and BRAF wild-type ( p= 0.0003 for comparison of CIMP). Conclusions: Genes under methylation regulation in the BRAF-mutant context showed enrichment in Wnt-signaling pathway. Since BRAFV600E CRC tumors have a low association with APC mutation, this data suggests role of epigenetic regulation of the Wnt-pathway activation. However, as measured by nuclear β-catenin, Wnt activation in these tumors is not as high as traditional APC-mutated CRC tumors. CIMP-H tumors with BRAFV600E mutation is a unique subset of CRC tumor that have Wnt-pathway activation regulated by epigenetic modifications more than a β-catenin activation.

Immunotherapy has recently become a major treatment modality for several types of solid tumours, achieving remarkable and long-lasting remissions. In metastatic colorectal cancer patients (mCRC), immune checkpoint inhibitors (ICIs) were found to be effective as treatment for deficient mismatch repair (dMMR)/ microsatellite instability high (MSI-H) tumours and received regulatory approval for this indication. However, mCRC is a complex disease and dMMR/MSI-H tumours represent a minority of the cases; therefore, new strategies are needed to extend the benefits of immunotherapy to a larger population of patients. This review explores the immunological differences between dMMR/MSI-H and proficient mismatch repair (pMMR)/ microsatellite instability low (MSI-L) tumours, focuses on new proposed biomarkers to predict response to immunotherapy and illustrates results reported from the main clinical trials with immunotherapeutic agents in CRC, addressing the most promising approaches being currently developed.

The EPHA2 tyrosine kinase receptor is implicated in tumor progression and targeted therapies resistance. We evaluated EPHA2 as a potential resistance marker to the antiepidermal growth factor receptor (EGFR) monoclonal antibody cetuximab in colorectal cancer. We studied activation of EPHA2 in a panel of human colorectal cancer cell lines sensitive or resistant to anti-EGFR drugs. The in vitro and in vivo effects of ALW-II-41-27 (an EPHA2 inhibitor) and/or cetuximab treatment were tested. Formalin-fixed paraffin-embedded tumor specimens from 82 RAS wild-type (WT) metastatic colorectal cancer patients treated with FOLFIRI + cetuximab as first-line therapy in the CAPRI-GOIM trial were assessed for EPHA2 expression by immunohistochemistry and correlated with treatment efficacy. EPHA2 was differentially activated in colorectal cancer cell lines. Combined treatment with ALW-II-41-27 plus cetuximab reverted primary and acquired resistance to cetuximab, causing cell growth inhibition, inducing apoptosis and cell-cycle G1–G2 arrest. In tumor xenograft models, upon progression to cetuximab, ALW-II-41-27 addition significantly inhibited tumor growth. EPHA2 protein expression was detected in 55 of 82 tumor samples, frequently expressed in less-differentiated and left-sided tumors. High levels of EPHA2 significantly correlated with worse progression-free survival [8.6 months; confidence interval (CI) 95%, 6.4–10.8; vs. 12.3 months; CI 95%, 10.4–14.2; P = 0.03] and with increased progression rate (29% vs. 9%, P = 0.02). A specific EPHA2 inhibitor reverts in vitro and in vivo primary and acquired resistance to anti-EGFR therapy. EPHA2 levels are significantly associated with worse outcome in patients treated with FOLFIRI + cetuximab. These results highlight EPHA2 as a potential therapeutic target in metastatic colorectal cancer.

Preclinical models, which are able to recapitulate the biology and pathology of the original individual cancer, are needed to better investigate mechanisms of response and resistance to anticancer therapies. In this respect, novel in vitro models for metastatic colorectal cancer could be of high value. Clin Cancer Res; 24(4); 727–9. ©2017 AACR. See related article by Luraghi et al., p. 807

Cetuximab and panitumumab, monoclonal antibodies direct against the epidermal growth factor receptor (EGFR) are a therapeutic option for mCRC patients wild type for KRAS and NRAS genes. However, only a subset of mCRC patients receives clinical benefit from these therapies due to the development of resistance mechanisms. HER2 gene amplification or HER2 activating mutations have been implicated as resistance mechanisms to anti-EGFR therapies. However, little is known about the role of HER2 in cancer resistance to anti-EGFR antibodies.

Purpose: The use of cetuximab in the treatment of metastatic colorectal cancer is limited by development of resistance. Experimental Design: We have investigated in three models of highly epidermal growth factor receptor (EGFR)–dependent colorectal cancer xenografts, the effect of maintenance therapy with different kinase inhibitors alone or in combination with cetuximab, after cytotoxic treatment induction with irinotecan plus cetuximab. Results: SW48, LIM 1215, and GEO colorectal cancer cell lines were engrafted into nude mice and treated for 3 weeks with irinotecan and/or cetuximab. The combined treatment induced a significant reduction of tumor size. A subsequent experiment was performed in all three xenograft models in which after an induction treatment with irinotecan plus cetuximab, mice were randomly assigned to one of the following treatments: control, cetuximab, regorafenib, a selective PIK3CA inhibitor (PIK3CAi), a selective MEK inhibitor (MEKi), and/or the combination of each inhibitor with cetuximab. The cetuximab plus MEKi treatment determined the best antitumor activity with suppression of tumor growth. This effect was prolonged for 13 to 15 weeks after cessation of therapy and was accompanied by prolonged survival. Antitumor activity was accompanied by inhibition of the MAPK and MEK pathways. Moreover, in the cetuximab plus MEKi-treated SW48 xenograft group, KRAS mutations as a mechanism of acquired resistance were detected in 25% of cases compared with 75% KRAS mutations in the MEKi-treated group. Conclusions: A possible strategy to prevent and/or overcome resistance to anti-EGFR inhibitors in metastatic colorectal cancer is a maintenance therapy with cetuximab plus MEKi after an initial treatment with irinotecan plus cetuximab. Clin Cancer Res; 21(18); 4153–64. ©2015 AACR.

Recent developments in genomic technologies have led an unprecedented view of the profound molecular complexity of colorectal cancer (CRC) and its evolution. The genomic landscape of CRC is characterized by a high heterogeneous landscape both at an intratumoral and at an inter-metastatic and intrametastatic level. In the era of personalized cancer medicine, the challenge is the definition of predictive biomarkers in respect of a such complex scenario. Despite the robust differences occurring between primary tumor and metastatic sites, the biomarkers currently validated in clinical practice have high concordance. The purpose of this review is to explore differences existing in genetic landscape of primary tumor and metastatic sites in CRC, in order to assess concordance and discordance rates of biologic events between different tumor lesions in CRC.

AXL is a tyrosine kinase receptor activated by GAS6 and regulates cancer cell proliferation migration and angiogenesis. We studied AXL as new therapeutic target in colorectal cancer (CRC). Expression and activation of AXL and GAS6 were evaluated in a panel of human CRC cell lines. AXL gene silencing or pharmacologic inhibition with foretinib suppressed proliferation, migration and survival in CRC cells. In an orthotopic colon model of human HCT116 CRC cells overexpressing AXL, foretinib treatment caused significant inhibition of tumour growth and peritoneal metastatic spreading. AXL and GAS6 overexpression by immunohistochemistry (IHC) were found in 76,7% and 73.5%, respectively, of 223 human CRC specimens, correlating with less differentiated histological grading. GAS6 overexpression was associated with nodes involvement and tumour stage. AXL gene was found amplified by Fluorescence in situ hybridization (FISH) in 8/146 cases (5,4%) of CRC samples. Taken together, AXL inhibition could represent a novel therapeutic approach in CRC.

Preclinical models, which are able to recapitulate the biology and pathology of the original individual cancer, are needed to better investigate mechanisms of response and resistance to anticancer therapies. In this respect, novel

// Stefania Napolitano 1 , Giulia Martini 1 , Erika Martinelli 1 , Carminia Maria Della Corte 1 , Floriana Morgillo 1 , Valentina Belli 1 , Claudia Cardone 1 , Nunzia Matrone 1 , Fortunato Ciardiello 1 and Teresa Troiani 1 1 Oncologia Medica, Dipartimento di Internistica Clinica e Sperimentale “F. Magrassi”, Universita degli Studi della Campania Luigi Vanvitelli, 80131 Naples, Italy Correspondence to: Teresa Troiani, email: teresa.troiani@unicampania.it Keywords: MM151, cetuximab, acquired resistance, epidermal growth factor receptor, metastatic colorectal cancer Received: April 13, 2017 Accepted: June 17, 2017 Published: August 02, 2017 ABSTRACT Purpose: We investigated the effect of triple monoclonal antibody inhibition of EGFR to overcome acquired resistance to first generation of anti-EGFR inhibitors. Experimental design: MM151 is a mixture of three different monoclonal IgG1 antibodies directed toward three different, non-overlapping, epitopes of the EGFR. We performed an in vivo study by using human CRC cell lines (SW48, LIM 1215 and CACO2) which are sensitive to EGFR inhibitors, in order to evaluate the activity of MM151 as compared to standard anti-EGFR mAbs, such as cetuximab, as single agent or in a sequential strategy of combination MM151 with irinotecan (induction therapy) followed by MM151 with a selective MEK1/2 inhibitor (MEKi) (maintenance therapy). Furthermore, the ability of MM151 to overcome acquired resistance to cetuximab has been also evaluated in cetuximab-refractory CRC models. Results: MM151 shown stronger antitumor activity as compared to cetuximab. The maintenance treatment with MM151 plus MEKi resulted the most effective therapeutic modality. In fact, this combination caused an almost complete suppression of tumor growth in SW48, LIM 1215 and CACO2 xenografts model at 30 week. Moreover, in this treatment group, mice with no evidence of tumor were more than double as compared to single agent treated mice. Its superior activity has also been demonstrated, in cetuximab-refractory CRC models. Conclusions: These results provide experimental evidence that more efficient and complete EGFR blockade may determine better antitumor activity and could contribute to prevent and/or overcome acquired resistance to EGFR inhibitors.

In the last two decades, great efforts have been made in the treatment of metastatic colorectal cancer (mCRC) due to the approval of new target agents for cytotoxic drugs. Unfortunately, a large percentage of patients present with metastasis at the time of diagnosis or relapse after a few months. The complex molecular heterogeneity of this disease is not completely understood; to date, there is a lack of predictive biomarkers that can be used to select subsets of patients who may respond to target drugs. Only the RAS -mutation status is used to predict resistance to anti-epidermal growth factor receptor agents in patients with mCRC. In this review, we describe approved targeted therapies for the management of metastatic mCRC and discuss new candidate targets on the horizon.

// Stefania Napolitano 1 , Giulia Martini 1 , Erika Martinelli 1 , Valentina Belli 1 , Alessia Parascandolo 2 , Mikko O. Laukkanen 2 , Vincenzo Sforza 1 , Floriana Morgillo 1 , Davide Ciardiello 1 , Fortunato Ciardiello 1 and Teresa Troiani 1 1 Oncologia Medica, Dipartimento Medico-Chirurgico di Internistica Clinica e Sperimentale “F. Magrassi e A. Lanzara”, Universita degli Studi della Campania Luigi Vanvitelli, 80131 Naples, Italy 2 IRCCS SDN, Via Gianturco, 80143 Naples, Italy Correspondence to: Teresa Troiani, email: tessy75@inwind.it Fortunato Ciardiello, email: fortunato.ciardiello@unina2.it Keywords: SYM004, cetuximab, acquired resistance, MET, metastatic colorectal cancer Received: December 05, 2016 Accepted: February 14, 2017 Published: June 27, 2017 ABSTRACT Purpose: Cetuximab and panitumumab have an effective therapeutic response in a subset of RAS Wild-Type (WT) metastatic colorectal cancers (mCRCs). Despite molecular-driven selection, all patients do not respond to epidermal growth factor receptor (EGFR) inhibitors and the onset of secondary resistance limits their clinical benefit. Experimental Design: We tested, in vitro and in vivo , the effect of SYM004, a 1:1 mixture of two recombinant human-mouse chimeric monoclonal antibodies (mAbs) directed against non-overlapping epitopes of the EGFR, on CRC models with acquired resistance to cetuximab. Results: SYM004 showed a potent growth inhibitory effect in CRC cell lines with acquired resistance to cetuximab and MET activation. SYM004 treatment determined a significant induction of apoptosis and a strong inhibition of MET, AKT and MAPK phosphorilation in these resistant models. The data may further suggest SYM004 -driven induced internalization and degradation of the antibody-receptor complex, which prevents cross-interaction between EGFR and MET even in the presence of TGFα. Moreover, in vivo xenograft studies demonstrated that SYM004 has stronger antitumor activity than cetuximab in CRC models. Importantly, in the current work we observed a response to therapy in all cetuximab resistant tumors mice treated with SYM004. More importantly, four out of seven mice continue to respond to SYM004 after 30 weeks of treatment underling the prolonged effect of the drug. Conclusion: These results suggest that the treatment with SYM004 could be a strategy to overcome acquired resistance to first generation of anti-EGFR therapies in mCRC as a result of MET activation.

Background TAS-102 improves overall survival (OS) in patients with metastatic colorectal cancer (mCRC) refractory to standard treatments. However, predictive biomarkers of efficacy are currently lacking. Patients and methods We treated a cohort of 43 chemorefractory mCRC patients treated with TAS-102, in a single institution expanded access, compassionate use programme. We stratified patients in two groups according to number of cycles received (

Please click here to see linked paper Background To investigate the potential predictors of response to regorafenib, in chemorefractory metastatic colorectal cancer (mCRC) patients with long-term efficacy from regorafenib treatment. Methods Retrospective, single institution analysis of patients with chemorefractory mCRC treated with regorafenib, in clinical practice setting. 123 patients were treated and stratified into two groups according to number of cycles received ( Results A good Eastern Cooperative Oncology Group performance status, a lung limited metastatic disease and a long history of metastatic disease were significantly associated with better OS and PFS from treatment with regorafenib. Mutations were mostly found in TP53 , KRAS and PIK3CA as well as in NRAS , ERBB2, SMAD4 and PTEN genes. BCL2L1, ERBB2, KRAS, MYC, GAS6 gene amplifications were detected as well as ALK rearrangement. No significant correlation between molecular alterations and response to regorafenib was observed. However, HER2 gene alterations were found in three poor responder patients, suggesting a potential role in regorafenib resistance. Conversely, GAS6 amplification and SMAD4 mutation, detected in two long responder patients, might suggest a role of epithelial–mesenchymal transition phenotype in regorafenib response. Conclusion A subgroup of long responder patients to regorafenib treatment was identified and a comprehensive molecular characterisation was performed; however, further research efforts are essential to confirm our data.

SUMMARY The prognosis of patients harboring metastatic colorectal cancer (CRC) remains poor despite therapeutic improvements obtained in recent years thanks to new biologic agents. A resistance mechanism limits the effectiveness of current cancer therapies to treat metastatic CRC patients. The identification of mechanisms of drug resistance may highlight new biomarkers useful to predict the clinical outcome or the likely responsiveness to pharmacological treatment of those metastatic CRC patients who cannot benefit from current therapeutic regimen. Moreover, the recognition of panels of biomarkers may suggest new strategies to overcome resistance by rational drug design and combination treatment. This review discusses CRC biomarkers, focusing initially on the most recent findings about the known ones, and mostly about the novel protagonists of this complex scenario.

To update the melanoma staging system of the American Joint Committee on Cancer (AJCC) a large database was assembled comprising >46,000 patients from 10 centers worldwide with stages I, II, and III melanoma diagnosed since 1998. Based on analyses of this new database, the existing seventh edition AJCC stage IV database, and contemporary clinical trial data, the AJCC Melanoma Expert Panel introduced several important changes to the Tumor, Nodes, Metastasis (TNM) classification and stage grouping criteria. Key changes in the eighth edition AJCC Cancer Staging Manual include: 1) tumor thickness measurements to be recorded to the nearest 0.1 mm, not 0.01 mm; 2) definitions of T1a and T1b are revised (T1a

Background Molecular mechanisms driving acquired resistance to anti-EGFR therapies in metastatic Colorectal Cancer (mCRC) are complex but generally involve the activation of the downstream RAS-RAF-MEK-MAPK pathway. Methods In order to understand the mechanism underlying MEK inhibitor (MEKi) resistance, we generated three different MEKi resistant models, two all RAS WT (SW48-MR and LIM1215-MR) and one mutated in RAS (HCT116-MR). Results These models showed features related to the gene signature of Colorectal Cancer CMS4 with upregulation of immune pathway as confirmed by Microarray and Western blot analysis. In particular, moving forward the MEKi phenotype we assisted to the loss of epithelial features and acquisition of mesenchymal markers and morphology. Moreover, this change in the morphology is accompanied by up-regulation of PD-L1 expression and activation of EGFR and its downstream pathway, independently of cell line status mutation. To extend these in vitro findings, we performed an in vivo study using MC38 and CT26 MEKi resistant syngeneic models that we have previously generated. Combined treatment of MEKi, EGFR inhibitor (EGFRi) and PD-L1inhibitor (PD-L1i) resulted in a marked inhibition of tumor growth in both MC38–MR and CT26-MR xenograft model. Conclusions These results suggest a strategy to potentially overcome immunotherapy resistance in CMS4-like tumors and to improve the efficacy of MEK inhibition by co-treatment with other agents providing an additional therapeutic strategy via modulation of host immune responses. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.

Background Historically, immunotherapies have been tested in syngeneic mouse models and until now only limited CRC syngeneic cells are available. Animal models with functioning human immune systems are critically needed to more accurately evaluate checkpoint blockers delivery, therapeutic response, and to better define biomarker expression in the presence of a competent immune system. Methods To better address the efficacy of immune checkpoint therapy specifically in relation to presence of a BRAFmutation, we developed a novel platform for the generation of somatic mosaic models of CRC enabling (i) high-throughput generation of genetically complex syngeneic models of cancer, (ii) tracing studies through fluorescence reporters. Results Cdx2Cre/+ mice, expressing the Cre recombinaseunder the control of a human Cdx2 promoter/enhancer sequence have been crossed with the R26LSL-Cas9-Gfp strain to generate models allowing for tissue specific activation of Cas9 and Gfpreporter only in CDX2 positive cells. This strain has been crossed with BRAFFSF-V600E mice to generate the final model. 6-8 weeks old mice have then been transduced with AAV constructs expressing the FLPO recombinasethat can be activated by Cre recombinase and sgRNAs targeting APC, TP53, MLH1, MSH2and ARID1Aalone or combined, in order to model MSI CRC (APC-TP53-MLH1and ARID1A-MLH1conditional mosaic knock-outs) and MSS CRC (APC-TP53 conditional mosaic knock-out). Viral particles have been surgically delivered via subserosal cecal injection and mice monitored for tumor formation by IVIS imaging. 35 mice injected with 3 combinations of tumor suppressors provide a diverse immunology repetoire. Cell lines isolated from genetically modified mice will provide a physiologic relevant and feasible means to study the mechanisms of response and resistance to immunotherapies and to understand biological and molecular differences between BRAFmutated MSI and MSS tumors. Conclusions This project focuses on the identification and characterization of the functional drivers of CMS1CRC tumors leveraging in vivomosaic genome editing technologies and functional genetic labeling of malignant sub-populations emerging during disease progression and in response to therapy. Legal entity responsible for the study The authors. Funding MD Anderson Cancer Center. Disclosure All authors have declared no conflicts of interest.

Background Anti-PD-1 antibodies represent nowadays a first-choice therapy for metastatic melanoma patients. Despite impressive results in terms of PFS and OS, a proportion of patients does not respond to anti-PD-1 therapy with an overall poor prognosis. Identification of predictive biomarkers is considered an important unmet clinical need to avoid expensive and potentially harmful drugs in patients who will not respond to them. In the last years, many studies have evaluated the role of cytokines on both blood and tissue samples as predictive biomarkers for immunotherapy, with encouraging results. Methods Blood samples from 18 patients with metastatic melanoma treated with anti-PD-1 antibodies as first line therapy were collected at baseline. 8 patients were classified as non-responders (best response: PD excluding pseudo-progression with median PFS of 2 months) and 10 patients as responders (best response: PR or CR, with median PFS of 17 months). mRNA expression levels of the main pro- and anti-inflammatory cytokines were evaluated by Real time quantitative PCR in PBMCs obtained from baseline blood samples. Unpaired two-tailed t-test was used for statistical analysis. Results IFN-γ mRNA expression levels were higher in responder patients (p 0.05). Combining data for each patient, we noticed a correlation between higher levels of IFN-γ and lower levels of IL-10 for responders and vice versa. Starting from these findings, we observed that the IFN-γ/IL-10 ratio was higher (median: 43,3 vs 5,2) in responders (p Conclusions Our data suggest an interesting correlation between IFN-γ/IL-10 ratio and response to anti-PD-1 therapy in melanoma patients. This correlation seems to be stronger than using IFN-γ expression levels alone probably because of the influence of anti-inflammatory cytokines. Since this is an exploratory and retrospective analysis of 18 patients, a larger population should be tested to validate our results. Legal entity responsible for the study Dipartimento di Medicina di Precisione, Universita degli studi della Campania Luigi Vanvitelli. Funding Has not received any funding. Disclosure F. Ciardiello: Advisory / Consultancy: Roche; Advisory / Consultancy: Amgen; Advisory / Consultancy: Merck; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Bayer; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Servier; Advisory / Consultancy: BMS; Advisory / Consultancy: Cellgene; Advisory / Consultancy: Lilly; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Roche; Research grant / Funding (institution): Merck; Research grant / Funding (institution): AstraZeneca; Research grant / Funding (institution): Amgen; Research grant / Funding (institution): Takeda. T. Troiani: Research grant / Funding (institution): Roche; Research grant / Funding (institution): Sanofi; Research grant / Funding (institution): Merck; Research grant / Funding (institution): Amgen; Research grant / Funding (institution): Servier; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Bayer. All other authors have declared no conflicts of interest.

Introduction: Fluoropyrimidines such as 5-fluorouracil (5-FU) and its orally active prodrug, capecitabine, are widely used in the treatment of gastrointestinal cancer, including colorectal cancer. Dihydropyrimidine dehydrogenase (DPD) plays an important role in the 5-FU metabolism. Dihydropyrimidine dehydrogenase gene (DPYD) is a highly polymorphic gene with several hundreds of reported genetic variants and DPD activity levels vary considerably among individuals, with different 5-FU-related efficacy and toxicity. About 5% of the population is deficient in DPD enzyme activity. The most well studied DPYD variant is the IVS14+1G>A, also known as DPYD ∗2A. In this report, we present a case of a patient with a double heterozygote DPYD variant (DPYD activity score: 0,5 according to Clinical Pharmacogenetics Implementation Consortium) who experienced a severe fluoropyrimidine-related toxicity resolved without any consequence. Patient concerns: A 46-years-old Caucasian man with diagnosis of left colon adenocarcinoma underwent left hemicolectomy on July 2017: pT3 G3 N1c M0. According to the disease stage, he started an adjuvant therapy with XELOX using capecitabine at 50% of total dose, because of his DPYD IVS14+1G>A variant, detected before the treatment. DIAGNOSIS: After few days, despite of this dose reduction, he experienced life-threatening adverse events such as mucositis G3, diarrhea G3, neutropenia G4, thrombocytopenia G4, and hyperbilirubinemia G3 according to Common Terminology Criteria for Adverse Events v 5.0. Interventions: As first, we set up an intensive rehydration therapy, antibiotic and antifungal prophylaxis, Granulocyte-Colony Stimulating Factors, and supportive blood transfusions. Additional genetic tests revealed a double heterozygote variant of DPYD gene (DPYD IVS14+1G>A and 2846A>T) which is a very rare situation and only 3 cases are described in literature, all of them concluded with patient's death. Outcomes: After 3 weeks of intensive therapy, the patient was fully recovered. Furthermore, all the whole-body CT scans performed since discharge from the hospital until now, have confirmed no evidence of disease. Conclusions: Recent studies demonstrated that screening strategy for the most common DPYD variants allowed for avoiding toxicities and saving money. This report underlines the importance of genotyping DPYD before treatment and emphasizes the role of genotype-guided dose individualization.

Background. Thrombotic microangiopathies (TMA) are relatively rare but severe disorders characterised by non-immune haemolytic anaemia, thrombocytopaenia and organ failure. In patients with metastatic cancer, sporadic forms of TMA can be triggered by chemotherapeutic agents or can occur as complication of malignancy itself or of infections. Case report. Hereby, we report a case of a patient diagnosed with metastatic colorectal cancer who experienced an atypical haemolytic-uraemic syndrome (aHUS) during chemotherapy treatment with FOLFOX6 scheme. The use of eculizumab led to prompt recovery of laboratory parameters that was maintained despite treatment discontinuation due to appearance of pneumonia infectious. Additionally, genetic analyses revealed the presence in heterozygosis of CFH gene polymorphisms associated with aHUS. Conclusion. This case emphasises the importance of considering TMA as a possible diagnosis in patients with cancer presenting with haemolytic non-immune mediate anaemia and thrombocytopaenia associated with worsening of renal function. Prompt diagnosis is crucial for the requirement of its specific treatment that can impact on long-term outcome and prognosis.

The prognosis of patients with metastatic colorectal cancer (mCRC) remain poor despite the impressive improvement of treatments observed over the last 20 years that led to an increase in median overall survival from 6 mo, with the only best supportive care, to approximately 30 mo with the introduction of active chemotherapy drugs and targeted agents. The monoclonal antibodies (moAbs) cetuximab and panitumumab, directed against the epidermal growth factor receptor (EGFR), undoubtedly represent a major step forward in the treatment of mCRC, given the relevant efficacy in terms of progression-free survival, overall survival, response rate, and quality of life observed in several phase III clinical trials among different lines of treatment. However, the anti-EGFR moAbs were shown only to be effective in a subset of patients. For instance, KRAS and NRAS mutations have been identified as biomarkers of resistance to these drugs, improving the selection of patients who might derive a benefit from these treatments. Nevertheless, several other alterations might affect the response to these drugs, and unfortunately, even the responders eventually become resistant by developing secondary (or acquired) resistance in approximately 13-18 mo. Several studies highlighted that the landscape of responsible alterations of both primary and acquired resistance to anti-EGFR drugs biochemically converge into MEK-ERK and PIK3CA-AKT pathways. In this review, we describe the currently known mechanisms of primary and acquired resistance to anti-EGFR moAbs together with the various strategies evaluated to prevent, overcame or revert them.

Epidermal growth factor receptor (EGFR) plays a key role in tumour evolution, proliferation and immune evasion, and is one of the most important targets for biological therapy, especially for non-small-cell lung cancer (NSCLC) and colorectal cancer (CRC). In the past 15 years, several EGFR antagonists have been approved for the treatment of NSCLC and metastatic CRC (mCRC). To optimise the use of anti-EGFR agents in clinical practice, various clinical and molecular biomarkers have been investigated, thus moving their indication from unselected to selected populations. Nowadays, anti-EGFR drugs represent a gold-standard therapy for metastatic NSCLC harbouring EGFR activating mutation and for RAS wild-type mCRC. Their clinical efficacy is limited by the presence of intrinsic resistance or the onset of acquired resistance. In this review, we provide an overview of the antitumour activity of EGFR inhibitors in NSCLC and CRC and of mechanisms of resistance, focusing on the development of a personalised approach through 15 years of preclinical and clinical research.

Objective To assess the feasibility of offering array-based comparative genomic hybridization testing for prenatal diagnosis as a first-line test, a prospective study was performed, comparing the results achieved from array comparative genomic hybridization (aCGH) with those obtained from conventional karyotype. Method Women undergoing amniocentesis or chorionic villus sampling were offered aCGH analysis. A total of 1037 prenatal samples were processed in parallel using both aCGH and G-banding for standard karyotyping. Specimen types included amniotic fluid (89.0%), chorionic villus sampling (9.5%) and cultured amniocytes (1.5%). Results Chromosomal abnormalities were identified in 34 (3.3%) samples; in 9 out of 34 cases (26.5%) aCGH detected pathogenic copy number variations that would not have been found if only a standard karyotype had been performed. aCGH was also able to detect chromosomal mosaicism at as low as a 10% level. There was complete concordance between the conventional karyotyping and aCGH results, except for 2 cases that were only correctly diagnosed by aCGH. Conclusions This study demonstrates that aCGH represents an improved diagnostic tool for prenatal detection of chromosomal abnormalities. Although larger studies are needed, our results provide further evidence on the feasibility of introducing aCGH as a first-line diagnostic test in routine prenatal diagnosis practice. Copyright © 2011 John Wiley & Sons, Ltd. Supporting information may be found in the online version of this article.

Nature Reviews Clinical Oncology, (2017). doi:10.1038/nrclinonc.2017.43 Jason J. Luke 0 0 2017-03-27T13:39:00Z 2017-11-29T14:35:00Z 1 312 1781 14 4 2089 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-US;} Regorafenib is a multikinase inhibitor currently approved for the treatment of chemorefractory mCRC patients. No predictive biomarkers of efficacy have been identified. We recently reported that amplification or mutations in HER-2/neu might predict resistance to regorafenib in a small cohort of patients treated with Regorafenib. We therefore sought to better investigate the role of HER-2/neu in response to Regorafenib in preclinical and clinical models. Short-term proliferation assay with Regorafenib was performed in a panel of CRC cell lines. Basal protein expression of total and phospho Her2 were analized by WB analysis. RPPA data from MD Anderson cell lines project were used for external validation of total and phospho HER-2/neu. Sperman correlation was applied to correlate the expression levels of total and phospo HER2/neu and IC50 to Regorafenib. HT29 CRC cell line (HT29) was made resistant to Regorafenib (HT29R). WB analysis of basal levels of proteins of the EGFR and Her2 axis were investigated in both HT29 and HT29R. Moreover, HT29 and HT29R were treated with EGFR inhibitors, Her2/neu inhibitors, MAPK and PIk3Ca inhibitors. Apoptosis was perfromed by FACs analysis by using Annexin-V staining. We found a negative correlation between pHer2 expression and response to Regorafenib in both our data set of CRC cell lines and in the MD Anderson panel. Overexpression of all the epitelial markers of the EGFR and HER2/neu axis was observed in HT29R as compared to HT29. This translated to an increased sensitivity and apoptosis to Trastuzumab in HT29R as compared to HT29 (IC50 with 50 times fold change) and PIk3Ca inhibitor (IC50 with 5 times fold change). No differences of IC50 were observed with other inhibitors. Moreover, combined treatment with Trastuzumab and PIk3Ca inhibitor induced significantly early and late apoptosis in HT29R as compared to HT29. Our preliminary data indicate pHer2 levels to be predictive of resistance to Regorafenib in CRC. Functional work and IHC analysis of CRC patients treated with Regorafenib is ongoing and will be presented. Citation Format: Loredana Vecchione, Stefania Napolitano, Valentina Belli, Erika Martinelli, Nunzia Matrone, Christophe Hapke, Ulrich Keilholz, Josep Tabernero, Fortunato Ciardiello, Teresa Troiani. Her2/neu expression as potential marker of regorafenib resistance in CRC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2841.

Molecular mechanisms driving acquired resistance to anti-EGFR therapies in mCRC is complex and biochemically converge to activate the EGFR-RAS-MAPK pathway. In order to understand the mechanism underlying MEKi resistance, SW48 MEKi resistant cell lines (SW48-MR) have been established by in vivo selection. To expand our results, another CRC cell line sensitive to MEK blockade, such as HCT116, has been generated: HCT116-MR. Microarray analysis showed that several genes involved in the PD-L1 pathway were up regulated in SW48-MR versus SW48. Moreover, genes overexpressed in MEKi-resistant tumor were related to the gene signature of CMS4 subtype of CRC. In particular all the pathways that were up regulated in CMS4 tumors were up regulated in the resistant cell line, as confirmed by Western blot and Immunofluorescence analysis. The regulation of PD-L1 expression is regulated by multiple signaling pathways, including JAK/STAT. STAT3 gene is also up regulated in MEKi-resistant tumors. Inhibition of STAT3 expression by siRNA reduced PD-L1 expression and restored MEKi sensitivity. Moreover, a direct correlation has been demonstrated between EGFR and PD-L1. Exogenous activation of EGFR by TGFα stimulation in MEKi sensitive HCT 116 cell lines induced PD-L1 overexpression and resistance to MEKi. Once demonstrated the EGFR role in modulation of PD-L1 expression and subsequently development of acquired resistance to MEKi, we further evaluated the potential mechanism(s) responsible for EGFR activation. One major mechanism is the specific ligand stimulation. Gene expressions analysis revealed that all EGFR ligands were up regulated in MEKi resistant tumors compared to parental tumors. Moreover, we will perform an ELISA assay to confirm this data. To extend these in vitro findings, we will perform an in vivo study using MC38 and CT26 MEKi resistant syngeneic models that we have previously generated. These results suggest a strategy to potentially improve the efficacy of MEK inhibition by co-treatment with other agents and provide an additional therapeutic strategy via modulation of host immune responses in CMS4 CRC tumors. Citation Format: Stefania Napolitano, Nunzia Matrone, Valentina Belli, Vincenzo De Falco, Erika Martinelli, Scott Kopetz, Fortunato Ciardiello, Teresa Troiani. PD-L1 pathway activation as an escape mechanism of resistance to MEK inhibitor treatment in human colorectal cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4904.

The article explores the political derivations of psychoanalytical discourse on femininity, starting from the impact of Lacanian positions on feminist thought. The consideration of a dimension of absolute otherness of female sexuality, irreducible to masculinity and to a phallic domain--not-all phallic--theorized by Lacan in the 1970s, opens up many complex issues for the politics of women's liberation. It is a matter of living the absolute difference without either radically excluding it from the speakable or letting it be part of a romantic imagery of the otherness that perpetuates sexual hierarchy and, consequently, female subordination. Taking up the proposal of such authors as Julia Kristeva or Silvia Tubert, we suggest that the Lacanian theory offers the conceptual tools to shift from exclusion to re-volt, from the place of the Other as a pedestal for the Same to a political function of female otherness and of the "not-all" that it represents: a part of the Kultur and its difficulties, but not entangled in it to the point that it cannot bring any innovation.

Purpose: In colorectal cancer, the activation of the intracellular RAS–RAF and PIK3CA–AKT pathways has been implicated in the resistance to anti-EGFR mAbs. We have investigated the role of regorafenib, an oral multikinase inhibitor, in combination with cetuximab, an anti-EGFR mAb, to overcome anti-EGFR resistance. Experimental Design: We have tested, in vitro and in vivo, the effects of regorafenib in a panel of human colorectal cancer cell lines with a KRAS mutation (SW480, SW620, HCT116, LOVO, and HCT15) or with a BRAF mutation (HT29), as models of intrinsic resistance to cetuximab treatment, and in two human colorectal cancer cell lines (GEO and SW48) that are cetuximab-sensitive, as well as in their derived cells with acquired resistance to cetuximab (GEO-CR and SW48-CR). Results: Treatment with regorafenib determined a dose-dependent growth inhibition in all colorectal cancer cell lines. The combined treatment with cetuximab and regorafenib induced synergistic antiproliferative and apoptotic effects in cetuximab-resistant cell lines by blocking MAPK and AKT pathways. Nude mice were injected s.c. with HCT116, HCT15, GEO-CR, and SW48-CR cells. The combined treatment caused significant tumor growth inhibition. Synergistic antitumor activity of regorafenib plus cetuximab was also observed in an orthotopic colorectal cancer model of HCT116 cells. In particular, the combined treatment induced a significant tumor growth inhibition in the primary tumor site (cecum) and completely prevented metastasis formation. Conclusions: The combined treatment with cetuximab and regorafenib could be a strategy to overcome resistance to anti-EGFR therapies in metastatic colorectal cancer patients. Clin Cancer Res; 21(13); 2975–83. ©2015 AACR.

Purpose: The EGFR-independent activation of the RAS/RAF/MEK/MAPK pathway is one of the resistance mechanisms to cetuximab. Experimental Design: We have evaluated, in vitro and in vivo, the effects of BAY 86-9766, a selective MEK1/2 inhibitor, in a panel of human colorectal cancer cell lines with primary or acquired resistance to cetuximab. Results: Among the colorectal cancer cell lines, five with a KRAS mutation (LOVO, HCT116, HCT15, SW620, and SW480) and one with a BRAF mutation (HT29) were resistant to the antiproliferative effects of cetuximab, whereas two cells (GEO and SW48) were highly sensitive. Treatment with BAY 86-9766 determined dose-dependent growth inhibition in all cancer cells, including two human colorectal cancer cells with acquired resistance to cetuximab (GEO-CR and SW48-CR), with the exception of HCT15 cells. Combined treatment with cetuximab and BAY 86-9766 induced a synergistic antiproliferative and apoptotic effects with blockade in the MAPK and AKT pathway in cells with either primary or acquired resistance to cetuximab. The synergistic antiproliferative effects were confirmed using other two selective MEK1/2 inhibitors, selumetinib and pimasertib, in combination with cetuximab. Moreover, inhibition of MEK expression by siRNA restored cetuximab sensitivity in resistant cells. In nude mice bearing established human HCT15, HCT116, SW48-CR, and GEO-CR xenografts, the combined treatment with cetuximab and BAY 86-9766 caused significant tumor growth inhibition and increased mice survival. Conclusion: These results suggest that activation of MEK is involved in both primary and acquired resistance to cetuximab and the inhibition of EGFR and MEK could be a strategy for overcoming anti-EGFR resistance in patients with colorectal cancer. Clin Cancer Res; 20(14); 3775–86. ©2014 AACR.

The epidermal growth factor receptor (EGFR) and its downstream signaling pathways are crucially important in the biology of colorectal cancer (CRC). In the past few years, EGFR kinase and its major downstream effector, the RAS/RAF/MAPK/ERK pathway, have been attractive targets for development of new therapy for treatment of metastatic CRC (mCRC). Cetuximab and panitumumab, two monoclonal antibodies (mAbs) against the EGFR, are the first targeted agents approved as personalized medicine for treatment of mCRC. Recently, inhibition of MEK1/2 has been seen as a promising approach for blocking MAPK-mediated proliferation signals. Several compounds with highly selective inhibitory effects on MEK1/2 have been developed and have entered clinical trials. New therapeutic agents have also been used to optimize personalized treatment of mCRC. In this context we discuss recent advances in research on EGFR and MAPK inhibitors.